Do bear in mind that if during a session you unplug your phone and plug it back in it'll show up as ttyACM1 or 2 or 3 each time you unplug but at reboot back to ttyACM0. You can reboot or change it in the preferences as needed just look on the list, no connection on ttyACM0 but ttyACM1 exists, ding ding ding, there's your solution.